The present invention relates to heat exchangers and especially to a new finned coaxial pipe heat exchanger.
This invention relates to a heat exchanger unit which can be utilized with solar heaters or with heat pumps, air conditioning systems or industrial cooling equipment. The heat exchanger unit is especially suited to transfer heat between one or more liquids circulating in the heat exchanger and the atmosphere in an efficient and reliable manner.
In the past, various types of dual pipe heat exchangers have been provided, such as a tubing spiralled around a center pipe for use in solar heaters or the like. Typical prior patents can be seen in my prior U.S. Pat. Nos. 2,023,417 and 2,037,378 and in U.S. Pat. No. 4,261,333 as well as in the references cited in the latter patent. The latter patent is directed primarily to a solar heat exchanger and avoids the problem of winding the tubing around a central pipe to make a more efficient heat exchanger. The present heat exchanger is formed out of coaxial pipe with a deep spiral groove having a generally square U-shape cross-section formed onto a central pipe. The grooves are found in the outer pipe with sufficient force to groove the central pipe so that the grooves from the outer pipe extend into the grooves formed in the center pipe to give a better contact between center and outer pipes for the transfer of heat. The spiral grooves in the center pipes also give a better flow pattern by the creation of a flow turbulence in fluid passing through the center pipe. The outer spiralling passageway is formed from a single outer pipe which requires connecting a spiralling passageway to a source of fluid, as well as connecting the center pipe to a second source of fluid without the fluids coming in contact. Special cooling fins are formed in the outer grooves in contact with the bottom of the grooves to provide additional transfer of heat from the center and outer pipes.